Well, if we're contemplating replacing the US Army's longest-lived light arm ever issued, why restrict ourselves to the 5.56mm ? Smaller or bigger caliber, there's lots of choices and lots of innovations in both chemistry and its ballistics impact to explore. Perhaps another stab at the "caseless" round ? Or, to satisfy the "antis" a "plastic case ala the Dardik "Tround" ? >MW

Or maybe it's time to just replace the M4 with a
Luke Skywalker flashlight and appease not only
the 'anti-gunners', but jobama's peaceful muslim
buddies also.
Don't you think they already have a handful of 'protos'
that manufacturers have presented, recently and in the past?
Must be a reason in someones wallet that they are even
considering this.